JP5933743B2 - Permanent magnet embedded motor, compressor, and refrigeration air conditioner - Google Patents

Description

  The present invention relates to an embedded permanent magnet electric motor, a compressor, and a refrigeration air conditioner.

  The electric motor mounted on the compressor of the refrigerating and air-conditioning apparatus is required to save energy and reduce noise, and must be used in a high temperature atmosphere of about 150 ° C. In general, Nd—Fe—B rare earth magnets have a high residual magnetic flux density and are suitable for miniaturization and high efficiency of electric motors, but the coercive force decreases as the temperature increases. Therefore, when a plurality of electric motors manufactured using this rare earth magnet are operated at the same current, the electric motor used in a high temperature atmosphere is more easily demagnetized. As a method for solving such a problem, a heavy rare earth element such as Dy (dysprosium) or Tb (terbium) is added to a rare earth magnet used in a high temperature atmosphere. As a result, an electric motor with improved coercive force and strong demagnetization can be obtained. However, in recent years, the rare value of heavy rare earth elements has increased, and the risk of procurement and price increases has increased. Reflecting such a situation, there is a demand for an electric motor that can be used without demagnetizing even a rare earth magnet having high efficiency, low noise, and low coercive force.

  In the conventional rotor described in Patent Document 1 below, permanent magnet insertion holes are formed in a rotor core on which a plurality of electromagnetic steel plates are laminated, and magnetic flux leakage prevention is provided on both sides in the circumferential direction of the permanent magnet insertion holes. Are provided with protrusions for fixing permanent magnets on both sides in the circumferential direction of the permanent magnet insertion holes. The magnetic flux leakage means that, for example, the magnetic flux at the circumferential end of the permanent magnet leaks to the adjacent permanent magnet via the electromagnetic steel plate between the magnetic poles or is short-circuited within the self magnet. As a result, in the conventional rotor, the permanent magnet is positioned and magnetic flux leakage is suppressed, so that a highly efficient electric motor can be obtained.

  The rotor is configured by combining the electrical steel sheet having the above-described protrusion and the electrical steel sheet not having the protrusion. The magnetic steel sheet having protrusions has a shorter distance between the front and back of the magnet than the magnetic steel sheet without protrusions, and the magnetic flux is easily short-circuited within the self-magnet. With this configuration, it is possible to position the permanent magnet inserted into the permanent magnet insertion hole, and it is possible to obtain a highly efficient electric motor with less leakage of magnetic flux by reducing the area of the electromagnetic steel sheet having protrusions. .

JP 2007-181254 A

  Here, in the permanent magnet motor, for example, when the load is large, when it is locked during operation due to overload, when it is in a transient state such as at startup, or when the stator winding is short-circuited A large armature reaction may occur, and a reverse magnetic field may be applied to the rotor. In particular, in the case of the concentrated winding method, the adjacent teeth instantaneously have different polarities, the inductance increases, and a reverse magnetic field is easily applied to the rotor. The reverse magnetic field is a magnetic field of a pole that is opposite to the direction of the magnetic pole of the rotor that is generated by energizing the stator.

  As in the conventional rotor shown in Patent Document 1, when a magnetic steel plate having a projection for fixing a permanent magnet and an electromagnetic steel plate not having this projection are combined, a demagnetizing magnetic flux due to a reverse magnetic field is reduced by a magnetic resistance. Avoiding a large flux barrier, it tries to pass through the protrusions, which are magnetic paths with low magnetic resistance. Therefore, there has been a problem that local demagnetization is likely to occur, such as demagnetizing magnetic flux concentrates in the region where the protrusion is provided, and a part of the permanent magnet adjacent to the protrusion is demagnetized.

  The present invention has been made in view of the above, and can suppress the demagnetization of the permanent magnet embedded in the rotor to further improve the reliability. And a refrigeration air conditioner.

In order to solve the above-described problems and achieve the object, the present invention is a permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is arranged in a stator core, The rotor core is composed of a plurality of first electromagnetic steel plates and a plurality of second electromagnetic steel plates stacked in the axial direction, and the magnetic poles of the rotor core are provided on the plurality of first electromagnetic steel plates. A plurality of magnet insertion holes for inserting the constituting magnets and first gaps formed at circumferential ends of the plurality of magnet insertion holes are formed, and the plurality of second electromagnetic steel plates include the plurality of the plurality of magnet insertion holes . and the magnet insertion holes, the projections for restricting the second gap formed in a circumferential direction at both ends of the plurality of magnet insertion holes, the positions of the plurality of said magnets are formed in the circumferential end of the radially inner side of the magnet insertion holes : it is formed, the plurality of second electromagnetic steel sheet, from said plurality of first electromagnetic steel plates That is laminated on at least one axial end of the electromagnetic steel sheet group, at least some of said plurality of second electromagnetic steel plates laminated in the axial end portion of the plurality of first electromagnetic steel sheet, the stator Provided at a position overhanging from the axial end of the core, the length from the axial center of the stator core to the axial end of the stator core is L1, and the axial center of the rotor core up to a length of the axial end portion of the rotor core and L2 from the L2 is larger than the L1.

  According to the present invention, by providing the second electromagnetic steel sheet having the protrusion at a position overhanging from the axial end of the stator core, the demagnetizing magnetic flux generated in the stator core is applied to the second electromagnetic steel sheet. Since it is difficult to flow, there is an effect that the demagnetization of the permanent magnet embedded in the rotor can be suppressed to further improve the reliability.

FIG. 1 is a cross-sectional view of a permanent magnet embedded electric motor according to an embodiment of the present invention. FIG. 2 is a perspective view of the rotor shown in FIG. FIG. 3 is a perspective view of the rotor core. FIG. 4 is a cross-sectional view of the rotor in plan view of the second electromagnetic steel sheet. FIG. 5 is a cross-sectional view of the rotor core in plan view of the second electromagnetic steel sheet. FIG. 6 is a cross-sectional view of the rotor in plan view of the first electromagnetic steel sheet. FIG. 7 is a cross-sectional view of the rotor core in plan view of the first electromagnetic steel sheet. FIG. 8 is a cross-sectional view of a main part of the rotor. FIG. 9 is a side view of the electric motor for explaining the flow of magnetic flux. FIG. 10 is a diagram showing the correlation between the overhang length of the second electromagnetic steel sheet with respect to the stator core and the demagnetization resistance. FIG. 11 is a diagram showing the demagnetization resistance of a conventional electric motor and the demagnetization resistance of the electric motor according to the embodiment of the present invention.

  Hereinafter, embodiments of an embedded permanent magnet electric motor, a compressor, and a refrigeration air-conditioning apparatus according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a cross-sectional view of an embedded permanent magnet electric motor (hereinafter “electric motor”) 100 according to an embodiment of the present invention. FIG. 2 is a perspective view of the rotor 30 shown in FIG. FIG. 3 is a perspective view of the rotor core 34. FIG. 4 is a cross-sectional view of the rotor 30 in plan view of the second electromagnetic steel plate 34b. FIG. 5 is a cross-sectional view of the rotor core 34 in plan view of the second electromagnetic steel plate 34b. FIG. 6 is a cross-sectional view of the rotor 30 in plan view of the first electromagnetic steel plate 34a. FIG. 7 is a cross-sectional view of the rotor core 34 in plan view of the first electromagnetic steel plate 34a. FIG. 8 is a cross-sectional view of the main part of the rotor 30. FIG. 9 is a side view of the electric motor 100 for explaining the flow of magnetic flux. FIG. 10 is a diagram showing a correlation between the overhang length of the second electromagnetic steel plate 34b and the demagnetization resistance with respect to the stator core 10. FIG. 11 is a diagram showing the demagnetization resistance of a conventional electric motor and the demagnetization resistance of the electric motor 100 according to the embodiment of the present invention.

  In FIG. 1, the electric motor 100 includes a stator core 10 and a rotor 30. For example, the stator core 10 is formed by stacking a plurality of electromagnetic steel sheets having a thickness of about 0.35 mm punched with a mold in the axial direction. The stator core 10 includes a yoke portion 11 and a plurality of teeth portions 12 extending inward from the yoke portion 11 and provided at equal intervals in the circumferential direction. A winding 51 (see FIG. 9) is wound around the tooth portion 12. In the electric motor 100, a rotating magnetic field is generated by energizing the stator core 10 with a current having a frequency synchronized with the command rotational speed, and the rotor 30 is rotated by the rotating magnetic field. A rotor 30 is disposed on the inner peripheral side of the stator core 10 via an air gap 20.

  The rotor 30 shown in FIG. 2 has a rotor core 34 and a permanent magnet 40 as main components. In FIG. 2, in order to make it easy to understand the relationship between a protrusion 35 and a permanent magnet 40 which will be described later, the outer core portion of the permanent magnet 40 shown on the front side in FIG. 2 is omitted. The permanent magnet 40 is, for example, a Nd—Fe—B rare earth magnet formed in a flat plate shape with a thickness of about 2 mm. The type of permanent magnet 40 is not limited to this.

  The rotor core 34 includes a plurality of first electromagnetic steel plates 34a (first electromagnetic steel plate group) stacked in the axial direction and a plurality of second electromagnetic steel plates stacked in the axial direction at both ends of the first electromagnetic steel plate group. It is comprised with the electromagnetic steel plate 34b (2nd electromagnetic steel plate group). The second electromagnetic steel plate 34b and the first electromagnetic steel plate 34a are manufactured, for example, by punching out an electromagnetic steel plate having a thickness of about 0.35 mm with a die.

  An insertion hole (shaft hole 32) of a shaft 50 (see FIG. 9) for transmitting rotational energy is provided at the center of the rotor core. The shaft hole 32 and the shaft 50 are connected by shrink fitting, press fitting, or the like. As shown in FIG. 3, the rotor core 34 is provided with magnet insertion holes 36 formed in the number of poles in the circumferential direction at equal intervals on the same circumference. The magnet insertion hole 36 has substantially the same shape as the permanent magnet 40. The magnet insertion hole 36 is provided in the vicinity of the rotor outer peripheral surface 38 between the rotor outer peripheral surface 38 and the shaft hole 32. Adjacent permanent magnets 40 are inserted into the magnet insertion holes 36 so as to have opposite polarities in the radial direction. This constitutes each magnetic pole. Note that the number of magnetic poles of the rotor 30 may be two or more, and in this embodiment, a configuration example of the rotor 30 having six magnetic poles will be described as an example.

  A plurality of slits 37 are provided in the iron core portion between the radially outer surface 36 a of the magnet insertion hole 36 and the rotor outer peripheral surface 38. The slit 37 is for suppressing the armature reaction magnetic flux from the stator core 10 to reduce sound vibration. Further, the rotor core 34 is provided with a plurality of air holes 31 that are air gaps that are refrigerant flow paths between the magnet insertion hole 36 and the shaft hole 32. The rotor core 34 is provided close to the inner diameter side surface 36 b of the magnet insertion hole 36. The second electromagnetic steel plate 34b and the first electromagnetic steel plate 34a are formed such that the slits 37 and the air holes 31 have the same shape.

  FIG. 4 shows a second electromagnetic steel plate 34 b in which the permanent magnet 40 is inserted into the magnet insertion hole 36, and FIG. 5 shows a second electromagnetic steel sheet in which the permanent magnet 40 is not inserted into the magnet insertion hole 36. A steel plate 34b is shown. The second electromagnetic steel plate 34b is formed with a magnet insertion hole 36, a second flux barrier 33b, which is a gap for preventing a magnetic flux short circuit, and a projection 35 for fixing the magnet. The protrusions 35 are formed at both ends in the circumferential direction of the radially inner side surface 36b of the magnet insertion hole 36, and are provided so as to protrude radially outward from the radially inner side surface 36b. The second flux barriers 33 b are provided on both sides in the circumferential direction of the magnet insertion hole 36.

  6 shows a first electromagnetic steel plate 34a in which the permanent magnet 40 is inserted into the magnet insertion hole 36, and FIG. 7 shows a first electromagnetic steel plate in which the permanent magnet 40 is not inserted into the magnet insertion hole 36. A steel plate 34a is shown. A magnet insertion hole 36 and a first flux barrier 33a that is a gap for preventing magnetic flux short-circuiting are formed in the first electromagnetic steel plate 34a. The first flux barriers 33 a are provided on both sides of the magnet insertion hole 36 in the circumferential direction. The first electromagnetic steel plate 34 a is not provided with the projection 35 of the second electromagnetic steel plate 34 b, and the inner diameter side surface 36 b of the magnet insertion hole 36 extends linearly to the vicinity of the gap 21.

  Thus, although the projection 35 is provided on the second electromagnetic steel plate 34b, the projection 35 is not provided on the first electromagnetic steel plate 34a. In the rotor 30 according to the present embodiment, by providing the projection 35 on the second electromagnetic steel plate 34b, the permanent magnet 40 is positioned at the center of the magnetic pole and is held so that the permanent magnet 40 does not move during driving. be able to. However, by providing the protrusion 35, the protrusion 35 becomes the shortest magnetic path to the magnet insertion hole 36, and the magnet magnetic flux (the magnetic flux between the adjacent permanent magnets 40) is easily short-circuited. Therefore, it is desirable that the height of the protrusion 35 (thickness t of the protrusion 35 shown in FIG. 4) be as small as possible (for example, about 1 mm) as long as the permanent magnet 40 can be held.

  Further, since the magnetic flux is easily short-circuited between the adjacent permanent magnets 40, the rotor 30 is designed so that the magnetic path is narrowed by the flux barriers (33a, 33b). The size of the flux barrier in the radial direction is, for example, the same size as that of the electromagnetic steel sheet (about 0.35 mm). With this configuration, short-circuiting of the magnetic flux at the end of the permanent magnet 40 is prevented, and this magnetic flux is easily transferred to the stator core 10 (see FIG. 1), and the generated torque can be increased.

  When the rotor 30 is manufactured, pressing may be performed by switching between a blade having the shape of the magnet insertion hole 36 having the protrusion 35 and a blade having the shape of the magnet insertion hole 36 having no protrusion 35.

  In FIG. 9, the axial length of the rotor core 34 is the rotor stack thickness X, the axial length of the stator core 10 is the stator stack thickness Y, and the axial end from the axial center of the stator core 10 is shown. The length L1 to the portion 10a, the length L2 from the axial center of the rotor core 34 to the axial end 34a, and the difference between the rotor product thickness X and the stator product thickness Y is defined as an overhang length Z To do.

  At this time, the rotor product thickness X is a size obtained by adding the second electrical steel plate group to the first electrical steel plate group, and the rotor product thickness X is formed larger than the stator product thickness Y. In the electric motor 100 according to the present embodiment, for example, the stator stack thickness Y is 40 mm and the rotor stack thickness X is 50 mm. The first electrical steel sheet group is formed so that the thickness thereof is smaller than the stator thickness Y. In addition, the second electrical steel sheet group provided at both ends of the first electrical steel sheet group is formed so that the thickness thereof is larger than the overhang length Z, for example. That is, a part of the second electromagnetic steel sheet group (the number of the second electromagnetic steel sheets 34 b is about several) is arranged at a position facing the stator core 10.

  The axial center of the stator core 10 and the axial center of the rotor 30 are arranged so as to substantially coincide with each other, the first electrical steel sheet group is provided at a position facing the stator core 10, and the second electrical steel sheet 34b. Is provided at a position overhanging from the axial end portion 10 a of the stator core 10. Accordingly, the overhang length Z is 10 mm, and the rotor protrudes from the stator by 5 mm at both ends in the axial direction. Note that the amount of protrusion of the rotor with respect to the stator may be asymmetric at both ends in the axial direction. The permanent magnet 40 inserted into the magnet insertion hole 36 has an axial length that is the same as the rotor stack thickness X.

  Here, the rotor 30 needs to ensure the holding strength of the permanent magnet 40 against the centrifugal force of the permanent magnet 40 generated by the rotation of the rotor 30 and the vibration of the permanent magnet 40 due to the electromagnetic force applied to the permanent magnet 40. There is. Therefore, when the above holding strength is insufficient, it is necessary to increase the axial thickness of the second electromagnetic steel sheet group.

  However, in the rotor 30, it is desirable that the ratio of the second electrical steel sheet group to the rotor 30 is small from the viewpoint of demagnetization. This will be specifically described below. FIG. 8 shows a cross section of a conventional electric motor. In the rotor of this electric motor, the second electromagnetic steel plate 34b1 in which the second flux barrier 33b and the protrusion 35 are formed is provided at a position facing the stator core 10. That is, the protrusion 35 is formed at a position facing the stator core 10. In the rotor, the distance from the radially outer surface 40 a of the permanent magnet 40 to the protrusion 35 is narrower than the thickness of the permanent magnet 40. Accordingly, the demagnetizing magnetic flux a avoiding the second flux barrier 33b having a large magnetic resistance tends to concentrate on the protrusion 35 having a small magnetic resistance. As a result, a part of the permanent magnet 40 adjacent to the protrusion 35 is demagnetized, and local partial demagnetization occurs.

  The permanent magnet 40 retains the original magnetic characteristics until the reverse magnetic field reaches a certain threshold value, but when this threshold is exceeded, the residual magnetic flux density decreases and the irreversible decrease does not return to the original magnetic characteristics. It becomes magnetic. When irreversible demagnetization occurs, the residual magnetic flux density of the permanent magnet 40 decreases, the current for generating torque increases, and not only the efficiency of the motor deteriorates, but also the controllability of the motor deteriorates, and reliability Bring about a decline. Such a problem can be solved by omitting the projection 35 from the magnet insertion hole 36. However, if there is no projection 35, it is difficult to arrange the permanent magnet 40 at the center of the magnetic pole. That is, when the permanent magnet 40 is displaced in the left-right direction with respect to the magnetic pole, the magnetic flux density distribution on the rotor surface becomes asymmetric with respect to the pole, resulting in the generation of sound vibration and a reduction in efficiency. Further, when the motor is driven, electromagnetic force acts on the permanent magnet, and the permanent magnet 40 may move and break, or the permanent magnet 40 may be a source of sound vibration.

  The conventional rotor shown in Patent Document 1 is configured by combining the electrical steel sheet having the projections 35 and the electrical steel sheet not having the projections 35. With this configuration, the permanent magnet can be positioned and the influence of leakage magnetic flux caused by the protrusion 35 can be reduced. However, when the axial thickness of the second electrical steel sheet group is increased in order to provide the above-described holding strength, the demagnetizing magnetic flux concentrates on the projection 35 having a small magnetic resistance, and the permanent magnet is adjacent to the projection 35. Partial demagnetization occurs in the magnet 40.

  In the electric motor 100 according to the present embodiment, as shown in FIG. 9, the first electromagnetic steel sheet group that does not have the protrusion 35 and is difficult to demagnetize is provided at a position facing the stator core 10, and the protrusion The second electromagnetic steel plate 34 b that has 35 and is easily demagnetized is provided at a position overhanging the axial end portion 10 a of the stator core 10. Since the second electromagnetic steel sheet group is a magnet-embedded electromagnetic steel sheet group, the magnetic flux b1 of the permanent magnet 40 provided in the second electromagnetic steel sheet group passes through the iron core on the rotor outer peripheral surface 38 side. As a result, the stator core 10 is linked while being curved in the radial direction. In addition, this Embodiment is an example at the time of being comprised so that an effect may be acquired to the maximum, and is not limited to this structure. For example, in order to improve the magnet insertion property, the effect can be obtained even when several second electromagnetic steel plates are arranged at positions facing the stator core 10 within a range where the influence of demagnetization is small. Moreover, in this Embodiment, although the 2nd electromagnetic steel plate group is arrange | positioned at the axial direction both ends of the 1st electromagnetic steel plate group, it is not limited to this. For example, the same effect can be obtained even when the second electromagnetic steel sheet group is arranged only on one of the axial ends of the first electromagnetic steel sheet group.

  On the other hand, since the demagnetizing magnetic flux a generated in the stator core 10 tends to pass through the portion having the smallest magnetic resistance, it is difficult to flow to the second electrical steel sheet group having a large magnetic resistance because it overhangs. As a result, local demagnetization is unlikely to occur in the second electromagnetic steel sheet group provided with the protrusions 35, and local demagnetization occurs even in the first electromagnetic steel sheet group not provided with the protrusions 35. Therefore, the demagnetization resistance can be improved.

  Further, in the rotor 30 according to the present embodiment, since the second electromagnetic steel sheet group is provided at both ends of the first electromagnetic steel sheet group at a predetermined interval, the insertability of the permanent magnet 40 is also excellent. .

  In the rotor 30 according to the present embodiment, after the permanent magnet 40 is positioned by the projection 35, for example, a tapered rod is inserted into the air hole 31, and this rod is inserted in the direction of the arrow shown in FIG. The thin portion 31a interposed between the radially inner side surface 36b of the magnet insertion hole 36 and the air hole 31 is deformed in the radially outward direction. As a result, the inner diameter side surface 36 b of the magnet insertion hole 36 is pressed against the inner diameter surface of the permanent magnet 40, and the permanent magnet 40 is held in the magnet insertion hole 36. Therefore, the above holding strength can be ensured without increasing the axial thickness of the second electrical steel sheet group. As a result, the projections 35 of the second electromagnetic steel sheet 34b need only have a positioning function in the circumferential direction of the permanent magnet 40, and the rotor 30 relatively reduces the axial thickness of the second electromagnetic steel sheet group. Can be small.

  In the table of FIG. 10, for example, assuming that the rotor thickness X is 50 mm, the ratio of the thickness of the second electrical steel sheet group at the position overhanging from the axial end portion 10 a of the stator core 10 is 0 mm. The demagnetization characteristic when changing from 10 mm to 10 mm is shown. The horizontal axis shows the ratio of the thickness of the second electrical steel sheet group, and the vertical axis shows the demagnetization resistance. For example, 0 mm on the horizontal axis represents a state where all the second electromagnetic steel sheet groups are disposed at positions facing the stator core 10. Further, 10 mm on the horizontal axis represents a state in which all the second electromagnetic steel sheet groups are disposed at positions overhanging from the axial end portion 10 a of the stator core 10. In FIG. 10, the demagnetization resistance is defined as follows. That is, a demagnetizing current is applied at a temperature (for example, about 150 ° C.) assuming the inside of the compressor (a demagnetizing magnetic flux is applied to the permanent magnet), and an induced voltage (when the motor is rotated by external power) It is defined as the ratio of the current value at which the generated voltage is reduced by 1% (irreversibly demagnetizing).

  As shown in FIG. 10, the demagnetization resistance is improved as the ratio of the thickness of the second electrical steel sheet group is increased from 0 mm. For example, when the thickness is 10 mm, the demagnetization resistance is improved by 5%.

  When the motor 100 is demagnetized, the performance of the compressor or refrigeration air conditioner on which the motor 100 is mounted fluctuates, and the voltage generated in the motor 100 changes, so the controllability of the motor 100 deteriorates. Therefore, in order to satisfy the reliability of the product, it is necessary to suppress the demagnetization factor to about 1%. In FIG. 11, the conventional electric motor has protrusions 35 formed on all the electromagnetic steel plates constituting the rotor core. When the demagnetization resistance of the conventional motor is compared with the demagnetization resistance of the electric motor 100 according to the present embodiment, the demagnetization resistance of the motor 100 is improved by 10% compared to the conventional motor. Therefore, when the electric motor 100 is used in the same current range as the conventional electric motor, the permanent magnet 40 having a coercive force lower than that of the permanent magnet used in the conventional electric motor can be used. That is, in the electric motor 100, the addition amount of heavy rare earth elements for improving the coercive force can be reduced, and the cost can be reduced.

  The breakdown of the improvement in the demagnetization resistance shown in FIG. 11 is improved by 5% by reducing the ratio of the first electrical steel sheet group provided with the protrusions 35, and the first electrical steel sheet group is replaced with the stator core 10. It is further improved by 5% by overhanging.

  Moreover, the electric motor 100 according to the present embodiment has the following effects regardless of the winding method, the number of slots, and the number of poles.

  (1) By providing the flux barriers (33a, 33b), it is possible to obtain a highly efficient electric motor 100 with less leakage magnetic flux and a highly reliable electric motor 100 in which the permanent magnet 40 is difficult to demagnetize.

  (2) Further, since the motor 100 that is resistant to demagnetization can be obtained, a magnet having a low coercive force can be used if the demagnetization resistance is equivalent to that of a conventional motor. It is possible to use an inexpensive rare earth magnet with a small amount. Reducing the addition amount of heavy rare earth elements improves the residual magnetic flux density of the magnet, so that the magnet torque is improved, the current for generating the same torque can be reduced, and the copper loss can be reduced, And it becomes possible to reduce the conduction loss of an inverter.

  (3) In addition, since the motor 100 that is resistant to demagnetization can be obtained, the permanent magnet 40 can be made thinner if a demagnetization resistance equivalent to that of a conventional motor is used, and an expensive rare earth magnet is used. It becomes possible to further reduce the manufacturing cost by suppressing the amount.

  (4) Further, by using the electric motor 100 according to the present embodiment, it is possible to obtain a highly reliable compressor and refrigeration air conditioner that are highly efficient, low noise, and difficult to demagnetize.

  (5) Further, in the rotor 30 according to the present embodiment, the permanent magnet 40 is fixed to the magnet insertion hole 36 by deforming, for example, the thin portion 31 a located in the radially outward direction of the air hole 31. When the rotor thickness X is 50 mm, in order to ensure the above-mentioned holding strength only by the second electromagnetic steel sheet group, the second electromagnetic steel sheet group needs to have a half thickness (25 mm) of 50 mm. In the rotor 30 according to the present embodiment, since the permanent magnet 40 is fixed at a portion other than the protrusion 35, the second electromagnetic steel plate 34b only needs to have a function of positioning the permanent magnet 40 in the circumferential direction. The thickness of the electrical steel sheet group 2 can be suppressed to about 10 mm. As a result, the area of the second electrical steel sheet group on which the protrusions 35 are formed can be reduced, and the overhang length Z can be reduced.

  The method of fixing the permanent magnet 40 is not limited to the method of deforming the air hole 31, and for example, the permanent magnet 40 may be bonded to the inner peripheral surface of the magnet insertion hole 36.

  Moreover, the values of the stator stack thickness Y and the rotor stack thickness X described in the present embodiment are examples, and the second electromagnetic steel plate 34b is overhanging from the axial end portion 10a of the stator core 10. If it is formed, it is possible to obtain the same effect as described above.

  Further, in the rotor 30 according to the present embodiment, all the second electromagnetic steel plates 34b constituting the second electromagnetic steel plate group are overhanging from the axial end portion 10a of the stator core 10. Although it is desirable, the same effect can be obtained if at least one second electromagnetic steel plate 34b is overhanging from the axial end portion 10a of the stator core 10.

  In the present embodiment, the second electromagnetic steel sheet group is provided at both ends of the rotor core 34. However, the second electromagnetic steel sheet group is provided only at one end of the rotor core 34. However, the same effect can be obtained.

  In addition, the electric motor 100 using the rotor 30 according to the present embodiment performs a variable speed drive by PWM control by an inverter of a drive circuit (not shown), thereby achieving a high efficiency according to a required product load condition. For example, when it is mounted on a compressor of an air conditioner, it can be used in a high temperature atmosphere of 100 ° C. or higher.

  As described above, the electric motor 100 according to the present embodiment includes the rotor core 34 including the plurality of first electromagnetic steel plates 34a and the plurality of second electromagnetic steel plates 34b that are stacked in the axial direction. The first electromagnetic steel plate 34a has a plurality of magnet insertion holes 36 into which the magnets (40) constituting the magnetic poles of the rotor core 34 are inserted, and first magnets formed at both ends in the circumferential direction of the magnet insertion holes 36. A gap (33a) is formed, and the second electromagnetic steel plate 34b has a plurality of magnet insertion holes 36, second gaps (33b) formed at both ends in the circumferential direction of the magnet insertion holes 36, and the magnets. Protrusions 35 are formed at both ends in the circumferential direction of the radially inner side surface 36b of the insertion hole 36 to restrict the position of the magnet, and the second electromagnetic steel plate 34b is an electromagnetic steel plate group composed of a plurality of first electromagnetic steel plates 34a. Laminated on at least one of the axial ends 10a, One is provided at a position overhanging from the axial end 10a of the stator core 10. With this configuration, the demagnetizing magnetic flux a generated in the stator core 10 does not easily flow to the second electromagnetic steel plate 34b, and the demagnetization of the permanent magnet 40 embedded in the rotor 30 is suppressed, thereby further improving the reliability. Thus, the electric motor 100 capable of achieving the above is obtained.

  Further, by mounting the electric motor 100 according to the present embodiment on a compressor and mounting the compressor on a refrigeration air conditioner, respectively, a highly reliable compressor or refrigeration that is highly efficient, low noise, and difficult to demagnetize. An air conditioner can be obtained.

  Note that the permanent magnet embedded electric motor, the compressor, and the refrigerating and air-conditioning apparatus according to the embodiment of the present invention show an example of the contents of the present invention, and can be combined with another known technique. However, it is needless to say that modifications can be made such as omitting a part without departing from the gist of the present invention.

  As described above, the present invention can be applied to a permanent magnet embedded electric motor, and is particularly useful as an invention capable of further reducing the manufacturing cost while improving the efficiency of the electric motor.

10 Stator Core, 10a Axial End, 11 Yoke, 12 Teeth, 20 Air Gap, 21 Pole, 30 Rotor, 31 Air Hole, 31a Thin Wall, 32 Shaft Hole, 33a First Flux Barrier (first 1), 33b second flux barrier (second gap), 34 rotor core, 34a first electromagnetic steel plate, 34b second electromagnetic steel plate, 34b1 second electromagnetic steel plate, 34c axial end, 35 Protrusions, 36 Magnet insertion holes, 36a Diameter outer surface, 36b Diameter inner surface, 37 Slit, 38 Rotor outer peripheral surface, 40 Permanent magnet, 40a Diameter outer surface, 50 Shaft, 51 Winding, 100 Embedded permanent magnet electric motor .

Claims (5)

A permanent magnet embedded electric motor in which a rotor core formed by laminating a plurality of electromagnetic steel plates is arranged in a stator core,
The rotor core is
It consists of a plurality of first electromagnetic steel plates laminated in the axial direction and a plurality of second electromagnetic steel plates,
In the plurality of first electromagnetic steel plates, a plurality of magnet insertion holes into which magnets constituting the magnetic poles of the rotor core are inserted, and first gaps formed at both circumferential ends of the plurality of magnet insertion holes, Formed,
In the plurality of second electromagnetic steel plates, the plurality of magnet insertion holes, second gaps formed at both ends in the circumferential direction of the plurality of magnet insertion holes, and radially inner surfaces of the plurality of magnet insertion holes Protrusions formed at both ends in the circumferential direction and restricting the position of the magnet are formed,
The plurality of second electromagnetic steel sheets are laminated on at least one of axial end portions of the electromagnetic steel sheet group composed of the plurality of first electromagnetic steel sheets,
At least a part of the plurality of second electromagnetic steel plates laminated on the axial end portions of the plurality of first electromagnetic steel plates is provided at a position overhanging from the axial end portion of the stator core,
The length from the axial center of the stator core to the axial end of the stator core is L1,
When the length from the axial center of the rotor core to the axial end of the rotor core is L2,
Said L2 is a permanent magnet embedded type electric motor larger than said L1. In the plurality of first electromagnetic steel plates and the plurality of second electromagnetic steel plates, gaps located between the plurality of magnet insertion holes and the rotor shaft are formed,
The thin portion interposed between the radially inner side surface of the plurality of magnet insertion holes and the gap is convex in the radially outward direction,
Wherein said magnet whose position is regulated by the projection, by the thin wall portion, the permanent magnet-embedded motor according to claim 1 situations that der held on the inner peripheral surface of said plurality of magnet insertion holes. Wherein said magnet whose position is regulated by the projections, the interior permanent magnet type electric motor according to claim 1 situations that der bonded to the inner peripheral surface of said plurality of magnet insertion holes.   A compressor equipped with the interior permanent magnet motor according to any one of claims 1 to 3.   A refrigeration air conditioner equipped with the compressor according to claim 4.

Images